Conversion of hydrocarbon oil



17, 1936. NELSQN 2,034,526

CONVERSION OF HYDROCARBON OIL Filed Oct. 25, 1953 INVENTOR UNlE SATES 2,034,526 CONVERSION OF ROCARBON OIL Edwin F. Nelson, Chicago, 111., assignor to Universal Oil Products Company, Chicago, 111., a

corporation of Delaware Application October 23, 1933, Serial No. 694,710

4 Claims.

This invention relates to improvements in the type of cracking process and apparatus wherein relatively low-boiling and relatively high-boiling oils are subjected to conversion in separate heating coils of the same cracking system and more specifically relates to the treatment of gaseous olefin hydrocarbons, together with said relatively low boiling hydrocarbon oil, by supplying the gases to the same cracking coil, for the purpose of obtaining polymerization of the gases and their combination with the oil undergoing treatment to produce additional yields of desirable light liquid products such as motor fuel of high anti knock value.

I have found that when hydrocarbon gases, particularly those of an unsaturated nature, or the relatively high-boiling olefin-containing gases resulting from the conversion of hydrocarbon oils for the production of high yields of motor fuel, are subjected to treatment together with lowboiling hydrocarbon oils, under the conditions of elevated temperature and high superatmospheric pressure required for the most satisfactory treatment of said low-boiling oils, there is an interaction between the gases and the oil undergoing treatment whereby an increased yield of desirable low-boiling distillate, such as motor fuel of high anti-knock value, is obtained with a corresponding decrease in the final yield of uncon- -densable gases from the process.

While no attempt is made in the present invention to fully explain or to account for the chemical reactions which may occur when olefin-containing gaseous hydrocarbons and light liquid hydrocarbons are subjected to treatment in commingled state under the conditions herein disclosed, the improved results obtainable, are believed to be due, at least in part, to polymerization of the gases (particularly their unsaturated components) and also to chemical combination between the gases and/or their polymerization products with the oil undergoing treatment and/or the conversion products resulting therefrom.

While the present invention is not limited to .the particular type of gaseous hydrocarbons employed nor to the particular type of oil with which they are subjected to treatment, I prefer to employ gases containing at least or thereabouts, of relatively high boiling unsaturated components such as ethylene, propylene and butylene and the liquid hydrocarbons with which they are subjected to heat and pressure treatment preferably comprise materials such as straight-run gasoline, naphtha, kerosene or kerosene distillate,

pressure distillate bottoms or the like which may be converted to produce high yields of good quality motor fuel at temperatures of from 950 to 1050 F. and superatmospheric pressures of from 500 to 1,000 pounds, square inch. 4

It is specifically within the scope of the present invention to subject gaseous hydrocarbons recovered by stabilization of the light motor fuel product resulting from the conversion of hydrocarbon oils to further treatment, together with low-boiling intermediate liquid products from the same cracking system, either liquid or gaseous hydrocarbons, or both, from any suitable external source being added, when desired, to the liquid and gaseous products of the process subjected to such further treatment and, in one of its more specific embodiments, the invention contemplates the treatment of low boiling liquid hydrocarbons and olefin-containing gaseous hydrocarbons in the heating coil of a cracking system simultaneous'with the conversion of higher boiling oils in a separate heating coil of the same system, the resulting conversion products from both heating coils being commingled in subsequent portions of the same cracking system.

One specific embodiment of the present invention comprises subjecting a hydrocarbon oil to conversion temperature at superatmospheric pressure in a heating coil and communicating reaction chamber, separating the resulting liquid and vaporous products, subjecting'the latter to fractionation whereby their components boiling above the range of the desired final light distillate product of the process are condensed as reflux condensate, separating the reflux condensate into low boiling and high boiling fractions, returning the latter to said heating coil for further conversion, subjecting fractionated vapors of the deor thereabouts, per

sired end-boiling point to condensation, collect-.

ing the resulting distillate and gas, subjecting the distillate to stabilization for the purpose of freeing the same of entrained gases and undesirable low boiling components, subjecting the liberated materials to cooling and condensation for the tions are described in connection with the following description of the accompanying diagrammatic drawing. The drawing illustrates one specific form of apparatus in which various phases of the invention may be practiced.

invention. Some of the many possible modifica- Raw oil charging stock for the process may-be supplied through line and valve 2 to pump 3, by means of which it may be fed, all or in part, either through line 4 and valve 5 into fractionator 6 or through line 1, valve 8 and line 9 direct to heating coil [0. The charging stock, if any, supplied to fractionator 6 serves to partially cool and assist fractionation of the vaporous products supplied to this zone, being preheated by direct contact therewith and collecting together with the reflux condensate recovered from the vapor-' ous conversion products subjected to fractionation. In the case illustrated high boiling fractions of the reflux condensate are withdrawn from the lower portion of fractionator 6 through line l l and valve |2 to pump l3, by means of which they are returned through line 9 and valve H to further conversion in heating coil [0. When the charging stock supplied to fractionator 6 is'of a relatively heavy nature, having an initial boiling point similar to that of the high boiling fractions of the reflux condensate withdrawn from the lower portion of the fractionator, as described, all or a substantial proportion of the charging stock will be supplied to heating coil l0 together with said high boiling fractions of the reflux condensate. When the charging stock is of a relatively low boiling nature, similar in end boil-. ing point to the low boiling fractions of the reflux condensate, all or a substantial proportion of the.

charging stock supplied to the fractionator will collect together with the low boiling fractions of the reflux condensate separately withdrawn from fractionator 6 and subjected to further treatment, as will be later more fully described. When a charging stock of relatively wide boiling range is employed substantial proportions thereof may be collected together with both the low boiling and high boiling fractions of the reflux condensate and subjected to further conversion therewith.

Heating coil I0 is located within a furnace l5 of any suitable form by means of which the required heat is supplied to the oil undergoing treatment to bring it ,to the desired conversion temperature, preferably ,at a substantial superatmospheric pressure, and the heated products are discharged through line l6- and valve into reaction chamber l8.

Chamber I8 is also preferably maintained at a substantial superatmospheric pressure and, although not illustrated in the drawing, it is preferably well insulated to prevent the excessive loss of heat by radiation so that conversion of the products supplied to this zone, and particularly their vaporous components, may continue therein. In the case here illustrated both vaporous and liquid conversion products are withdrawn from the lower portion of. chamber l8 and supplied through line l9 and valve 29 to vaporizing chamber 2|.

Chamber 2| is preferably maintained at a substantially reduced pressure relative to that employed in chamber l8 by means of which further vaporization of the liquid conversion products supplied to this zone is accomplished. Liquid conversion products remaining unvaporized in chamber 2| may be withdrawn therefrom through line 22 and valve 23 and, in the case here illustrated, pass through heat exchanger 24, line 25 and valve 26 to cooling and storage or to any desired further treatment. The vaporous conversion products are withdrawn from the upper portion of chamber 2| and directed through line 21 and valve 28 to fractionation in fractionator 6.

It is within the scope of the present invention,

when desired, to control the operating conditions of the process so that only substantially dry coke is produced as the residual product of the. process, in which-case the coke may be allowed to accumulate within chamber 2| to be removed therefrom in any well known manner (not shown) after the operation of the chamber is completed. When desired, a plurality of coking chambers similar to chamber 2| may be employed, although only a single chamber is shown in the drawing, in order to provide additional space for the deposition of coke, in which case they may be operated simultaneously or, preferably,-are alternately operated, cleaned and prepared for further operation so that the duration of the operating cycle will not be limited by the capacity of the coking zone.

The components of the vaporous conversion products supplied to fractionator 6, boiling above the range of the desired final light distillate product of the process, are condensed in this zone as reflux condensate.- In the case here illustrated, the reflux condensate is separated into relatively low boiling and relatively high boiling fractions, the latter being withdrawn from the lower portion of the fractionator and returned, as already described, to heating coil ID for further conversion while the low boiling fractions are separately withdrawn from one or any number of suitable intermediate points in the fractionator, for example, through line 29 and valve 30 to pump 3| by means of which they are supplied through line 32, valve 33, line 34, line '35 and valve to further conversion in heating coil 36, as will be later more fully described.

Fractionated vapors of the desired end boiling point are withdrawn, together with uncondensable gas produced by the process, from the upper portion of fractionator 6 through line 31 and valve 38 and are subjected to condensationand cooling in condenser 39. The resulting distillate and gas passes through line 40 and valve 4| to collection and separation in receiver 42. Uncondensable gas may be released from the receiver through line 43 and'valve 44 and may, when desired, be subjected to absorption or scrubbing in any well known manner (not shown). Distillate collecting in receiver 42 may be withdrawn therefrom through line 45 and valve 46 to pump 41 by means of which it is directed to suitable stabilizing equipment, as will be later more fullydescribed. A regulated portion of the distillate collecting in receiver 42 may, when desired, be returned to the upper portion of fractionator 6 to serve as cooling and refluxing medium to assist fractionation of the vaporous products in this zone and to regulate the vapor outlet temperature from the fractionator. This may be accomplished, in the case illustrated, by means of line 48 and valve 49.

by indirect contact and heat exchange with other hot vaporous and/or liquid products of the process or by passing the same through a heating coil which may be independently fired or may be heated, for example, by combustion gases from either or both cracking furnaces of the process. When desired, other unstabilized distillate from another cracking system or from any other desired external source may be supplied to stabilizer 56 in heated state by means of line 51, valve 58 and line 55.

Stabilizer 56 may be provided with a suitable reboiling coil 59, controlled by valves 66 and 6|, through which any suitable heating medium such as steam, hot oil, in either liquid or vaporous state, from within the system or from any desired external source, or the like may be circulated for the purpose of reboiling the distillate collecting in the lower portion of this zone. The reboiled and stabilized distillate may be withdrawn from the lower portion of stabilizer 56 to cooling and storage or to any desired further treatment through line 62 and valve 63.

A suitable cooling coil 66 may be provided within the upper portion of the stabilizer through which any suitable cooling or refrigerating medium may .be passed, controlled by valves 65 and 66, for the purpose of preventing the escape of vaporized components of the distillate which are desirable as components of the stabilized distillate and to regulate the outlet temperature and composition of the gaseous products which are withdrawn from the upper portion of the stabilizer through line 61 and valve 68 to cooler and condenser 69. Heavy components of the gases such as butylene, propylene, ethylene and the corresponding saturated compounds may be condensed by indirect contact with any suitable cooling and refrigerating medium in condenser 69 and the resultin'g liquid and gaseous products pass'through line ill and valve H to collection and separation in receiver 12. When desired, single or multiple stage compression may be employed for condensing or assisting in the condensation of the desirable-components of the gases, although well known means for accomplishing this are not shown in the drawing. 'Uncondensed gases may. be removed from receiver 12 through line l3 .and valve 74. The liquefied components of the gases are Withdrawn from receiver 72 through line 15 and valve 16 to pump 'il by means of which they are supplied through line .34, valve 18, line and valve 90 to heating coil 36 for further treatment, together with low boiling fractions of the reflux condensate from fractionator 6, supplied to heating coil 36 as previously described. A regulated portion of the liquid withdrawn from receiver 72, as described, may when desired be returned by means of line 79 and valve 86 to the upper portion of stabilizer 56 for the purpose of assisting cooling and fractionation in this zone. This method of cooling, when employed, may be used in conjunction with or may take the place of cooling coil 64, previously described.

When desired, olefin-containing gases from any suitable external source may be supplied to heating coil 36 by means of line 8i. valve 82, pump 33. line 84, valve 85 and lines 34 and 35 and valve 90'. This may comprise, for example, gases of suitable composition from another cracking system or desirable components of the 1 gaseous products from receiver 62 recovered therefrom by compression, absorption or in any other suitable manner (not shown).

It is also within the scope of the present invention, when desired, to supply suitable low boiling hydrocarbon oil such as, for example, gasoline 'of poor anti-knock value, naphtha, kerosene or kerosene distillate, pressure distillate bottoms or the like from any suitable source to heating coil 36 for conversion or reforming. This is accomplished, in the case illustrated, by means of line 86, valve 81, pump 88, line 89, valve 90, line 35 and valve 96'. When distillate is supplied in this manner to heating coil 36 for treatment. together with olefin-containing normally gaseous products from within the system or from an external source, it maybe utilized in conjunction with or may replace low boiling fractions of the reflux condensate from fractionator6, in which latter case the total reflux condensate from fractionator 6 may be returned, when desired, to further conversion in heating coil 86 or, when desired the total or selected low boiling or high boiling fractions of the reflux condensate may be removed from the system by well known means (not shown).

It is also within the scope of the present invention, particularly in case the charging stock supplied to heating coil i0 is a relatively light oil and when high boiling reflux condensate is not returned to the heating coil, to supply the olefincontaining gases to heating coil l0 instead of employing heating coil 36 for this purpose. This may be accomplished, in the case here illustrated, by means of line 9! and valve 92 whereby the materials supplied to line 35, as previously described, may be diverted to line 9 and thence to heating coil ill.

A furnace 93 of any suitable form supplies the required heat to the commingled materials passing through heating coil 36 to bring them to the desired relatively high temperature, preferably at substantial superatmospheric pressure, and the heated products are discharged through line 96 and may be directed, for example, either through valve 95, in this line, into reaction chamber I8 or through line 96 and valve 91 into vaporizing or coking chamber 2! or the heated products from heating coil 36 may be supplied, in part, to both chambers l8 and H. When the highly heated products from heating coil 36 or a regulated portion thereof are supplied to chamber l6 they commingle in this zone with the conversion products from heating coil ID, the commingled materias being subjected to further treatment and interaction in the reaction chamber. When supplied to chamber 2| highly heated products from heatng coil 36 may be introduced, for example, into the lower portion of this zone, as illustrated in the drawing, to commingle with and assist vaporization of the residual conversionproducts therein, serving, when desired, as a means of effecting their reduction to coke. It is, of course, also within the scope of the present invention to supply the highly heated products from heating coil 36 into chamber 18 and/or chamber 2i at any desired point or plurality of points (not shown) or to line l9 between chambers l8 and 2| or direct to fractionator 6.

In an apparatus such as illustrated and above described, the operating conditions of the process per square inch are preferably employed at the outlet from the heating coil to which the olefincontaining gases and low boiling oil are supplied.

The pressure employed in the reaction chamber preferably is substantially equalized with that employed at the outlet from the heating coil utilizing the lowest pressure, in case two heating coils are employed at different pressures, although a somewhat reduced pressure'may be utilized in the reaction chamber, when desired.

, The vaporizing or coking chamber preferably employs a substantially reduced pressure relative to that in the reaction chamber, which reduced pressure may range, for example, from 100 pounds, or thereabouts, per square inch to substantially atmospheric pressure. The pressures employed in the fractionating, condensing and collecting portions of the cracking system may be either substantially equalized or somewhat reduced relative to the pressure employed in the vaporizing or coking chamber. The stabilizing column is preferably operated at substantially atmospheric pressure, although any desired pressure up to 150 pounds, or more, per square inch, may be employed in this zone, when desired. As previously indicated the collecting or con densing and collecting portions of the stabilizing system may be operated at high superatmospheric pressure when compression is employed as a means of liquefying the desirable components of the gases.

As a specific example of one of the many possible operations of the process of the present invention utilizing as charging stock a Midcontinent fuel oil of about 26 A. P. I. gravity; this material is supplied to the: fractionator of the cracking system wherein it is separated, together with the reflux condensate, into low boiling and high boiling fractions, the high boiling fractions are subjected to a conversion temperature, measured at the outlet from the heating coil to which they are supplied, of about 900 F. at a superatmospheric pressure of approximately 400 pounds per square inch, substantially the same pressure is employed in the reaction chamber and is reduced in the vaporizing chamber to approximately 60 poundsper square inch, substantially equalized pressure being utilized in the succeeding portions of the cracking system. Low boiling fractions of the reflux condensate and charging stock are supplied, together with liquefied components of the gaseous products recovered by stabilization of the motor fuel product of the process, containing a substantial proportion of ethylene and propylene as well as some butylene, to a separate heating coil wherein they are subjected to further treatment in commingled state, a temperature of approximately 1000 F. being employed at the outlet from this zone with asuperatmospheric pressure, measured at this point in the system, of approximately 750 pounds per square inch. 'This operation may yield, per barrel of charging stock, approximately 58% of 400 F. end-point motor fuel of good anti-knock value, about 440 cubic feet of gas and about 32% of good quality fuel oil residue. This compares with a yield of approximately 55% of motor fuel' and about 500 cubic feet of gas, per barrel of charging stock produced by a similar operation wherein olefin-containing gases are not suppliedoil wherein relatively low boiling and relatively high boiling oils are subjected to independently controlled conversion conditions of elevated temperature and superatmospheric pressure in separate heating coils, the resulting vaporous and liquid conversion products separated, the vapors subjected to fractionation for the removal therefrom of reflux condensate, comprising their insufiiciently converted components boiling above the range of the desired final light distillate product of the process, fractionated vapors of the desired end-boiling point subjected to condensation, the resulting distillate and gas collected and separated and the distillate subjected to stabilization for the removal therefrom of undesirable normally gaseous materials, the improvement which comprises condensing high boiling components of said normally gaseous materials and returning the same to further treatment, together with said low-boiling oil in the heating coil to which it is supplied, and commingling the highly heated products therefrom with the products resulting from conversion of the higher boiling oil, prior to their fractionation.

2. A process of the character defined in claim 1, wherein the reflux condensate is separated into low-boiling and high-boiling fractions, the lowboiling fractions returned for further treatment to the heating coil to which the higher boiling components of said normally gaseous materials are supplied and the high-boiling fractions returned to the other heatingcoil of the process for further conversion.

3. A conversion process which comprises subjecting hydrocarbon oil to cracking conditions of temperature and pressure, fractionating the resultant vapors to condense fractions thereof heavier than gasoline, finally condensing the fractionated vapors and separating the resultant condensate from incondensible gases, stabilizing the final condensate to separate therefrom fractions too volatile as constituents of motor fuel, combining such volatile fractions with a hydrocarbon oil of lower boiling point than the firstnamed oil, heating the resultant mixture independently of and to higher cracking temperature than the first-named oil, combining products of this independent heating with conversion products of the first-named oil, and recovering the stabilized final condensate as a product of the process.

the vapors to form relatively heavy and light reflux condensates, returning such heavier refiux to the heating zone, finally condensing the fractionated vapors andseparating the resultant condensate from incondensible gases, stabilizing the final condensate to separate therefrom fractions too volatile as constituents of motor fuel,

combining such volatile fractions with lighter reflux condensate formed by said fractionation and heating the resultant mixture in a second heating zone to higher cracking temperature than the oil in the first-named heating zone, combining heated products from said second zone with heated products from the first-named heating zone and fractionating the vapors evolved from said mixture together with the first-named vapors, and recovering the stabilized condensate as a product of the process.

' EDWIN F. NELSON. 

